Field of the Invention (Technical Field)
The present invention relates to a method for placement of a subterranean curtain below the face of the earth.
Description of Related Art Including Information Disclosed Under 37 C.F.R. §§ 1.97 and 1.98:
U.S. Pat. No. 5,118,230 discloses a trenching tool which digs a trench to depth of 6 to 30 feet (2 to 10 m). A liner carrier case is conveyed to the trench bottom from which is withdrawn an impermeable barrier liner which extends from the bottom to the top of the excavated trench. The impermeable liner is deployed simultaneously with the trenching operation. After placement of the liner the trench is backfilled with material previously dug from the trench.
U.S. Pat. No. 5,915,878 discloses a device for slicing through soil and simultaneously inserting a silt fence into the soil. The silt fence is a synthetic material installed in and above the ground to impede silt erosion from areas disturbed by a construction. The device thinly slices through the soil 8 to 12 inches deep (2.6 to 4 m). It includes a vertical wheel operating between two parallel panels, acting as a moving pivot point where the horizontal silt fence is converted to a vertical position between the panels. The panels hold the soil open while the vertical wheel simultaneously inserts the silt fence into the opening. As the machine progresses, soil collapses against the silt fence, thus securing the silt fence in the desired position.
U.S. Pat. No. 5,685,668 discloses an apparatus for delivering liner material into a trench, that provides continuous rolls of liner material which are joined by vertical and horizontal seams to accommodate the desired length or configuration of placement. To initiate unrolling of a length of liner material, a roll of material is dropped into the installation apparatus which trenches into the subsurface. One end of the liner material is held in place by restraints and hydraulic presses. The roll is then unrolled by trenching backwards, cutting a trench and unfurling the roll in the formed trench.
EP-A-0 191 533 discloses laying a sheet of material in the ground by digging a trench by means of a trench digger and unwinding a sheet of material from a stock roll above ground level, passing it into the trench in a downward direction and diverting it in a direction essentially parallel to ground level. The sheet of material is folded twice and passed down in the trench, and is passed further via three return rollers or rods or flanges in the unfolded state in an approximately vertical plane in the horizontal direction.
EP-A-0 277 670 discloses a method for installing a screen of flexible material in the soil, wherein a trench is dug in the soil and the screen is fed into the trench. The screen is provided by facilities to prevent its sagging into the still unfilled trench by providing a wire strung through the top edge of the screen which is held under a certain tension, and wherein a strip is applied which is bonded along the top edge of the screen or an inflatable sleeve fitted to the top edge of the screen. The screen may be provided as a sleeve fillable with gas, liquid or a substance.